Extracellular vesicles: A promising therapy against SARS-CoV-2 infection
Authors: Yan Leyfman, Greta Gohring, Muskan Joshi, Gayathri Pramil Menon, Alexandra Van de Kieft, Tania del Rivero, Michael A. Bellio, Maria Ines Mitrani
Journal: Molecular Therapy (2023)

Severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) has infected over 650 million people and claimed the lives of nearly 7 million since the start of the pandemic. While SARS-CoV-2 is becoming endemic with several preventative therapies, an effective treatment against severe disease remains unavailable. Immunocompromised patients remain vulnerable given the limited efficacy of vaccinations and are at risk of respiratory failure, organ failure, and septic shock if infected.1Stawicki S.P. Jeanmonod R. Miller A.C. Paladino L. Gaieski D.F. Yaffee A.Q. De Wulf A. Grover J. Papadimos T.J. Bloem C. et al.The 2019–2020 novel coronavirus (severe acute respiratory syndrome coronavirus 2) pandemic: a joint american college of academic international medicine-world academic council of emergency medicine multidisciplinary COVID-19 working group consensus paper.J. Glob. Infect. Dis. 2020; 12: 47-93https://doi.org/10.4103/jgid.jgid_86_20Crossref PubMed Scopus (197) Google Scholar The development of therapeutics to combat the progression and severity of SARS-CoV-2 infection presents an opportunity to explore innovative approaches to treating viral diseases. Novel therapeutic strategies aim to target the host response to hyper-inflammation and prevent the cytokine storm that is often associated with severe COVID-19 cases.2Dorward D.A. Russell C.D. Um I.H. Elshani M. Armstrong S.D. Penrice-Randal R. Millar T. Lerpiniere C.E.B. Tagliavini G. Hartley C.S. et al.Tissue-specific immunopathology in fatal COVID-19.Am. J. Respir. Crit. Care Med. 2021; 203: 192-201https://doi.org/10.1164/rccm.202008-3265OCCrossref PubMed Scopus (160) Google Scholar In recent years, researchers have focused on intracellular secreted factors, such as extracellular vesicles (EVs), to improve and build upon the knowledge gained from cell-based research and spearhead the use as potential therapeutic agents for various diseases, including SARS-CoV-2. EVs are small membranous structures secreted by the cell membrane or the cell's internal recycling pathways and have emerged as a promising therapeutic strategy due to their involvement in a range of biological processes, including cell signaling, immune response, and disease progression. The objective of this analysis is to examine the potential efficacy of EV-based therapies in the treatment of SARS-CoV-2 severity, with a particular emphasis on their common mechanisms and suitability for future therapeutic use in human patients. Severe SARS-CoV-2 acts via direct and indirect pathways to cause local and systemic injury. In the direct pathway, severe SARS-CoV-2 utilizes its spike protein to bind to angiotensin-converting enzyme 2 (ACE-2), allowing entry into cells. Cells in the nasopharyngeal tract and lungs are most prone to damage by SARS-CoV-2 due to higher cell surface expression of the ACE-2 receptor.3Yan R. Zhang Y. Li Y. Xia L. Guo Y. Zhou Q. Structural basis for the recognition of SARS-CoV-2 by full-length human ACE2.Science. 2020; 367: 1444-1448https://doi.org/10.1126/science.abb2762Crossref PubMed Scopus (3130) Google Scholar,4Sungnak W. Huang N. Bécavin C. Bécavin C. Queen R. Litvinukova M. Talavera-López C. Talavera-López C. Reichart D. Sampaziotis F. et al.SARS-CoV-2 entry factors are highly expressed in nasal epithelial cells together with innate immune genes.Nat. Med. 2020; 26: 681-687https://doi.org/10.1038/s41591-020-0868-6Crossref PubMed Scopus (1598) Google Scholar After direct cellular entry, SARS-CoV-2 replicates using host machinery, and viral-mediated damage results in the secretion of pro-inflammatory cytokine interleukin-6 (IL-6).5Narazaki M. Kishimoto T. The two-faced cytokine IL-6 in host defense and diseases.Int. J. Mol. Sci. 2018; 19: 3528https://doi.org/10.3390/ijms19113528Crossref PubMed Scopus (122) Google Scholar Clinically, this presents with anosmia and ageusia with rapid progression to dyspnea and respiratory failure, ultimately resulting in multi-organ damage.6Renieris G. Katrini K. Damoulari C. Akinosoglou K. Psarrakis C. Kyriakopoulou M. Dimopoulos G. Lada M. Koufargyris P. Giamarellos-Bourboulis E.J. Serum hydrogen sulfide and outcome association in pneumonia by the SARS-CoV-2 coronavirus.Shock. 2020; 54: 633-637https://doi.org/10.1097/SHK.0000000000001562Crossref Scopus (58) Google Scholar The virus also acts via an indirect pathway to induce systemic injury. SARS-CoV-2-infected cells can undergo pyroptosis, which leads to the release of damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs).7Wang M. Chang W. Zhang L. Zhang Y. Pyroptotic cell death in SARS-CoV-2 infection: revealing its roles during the immunopathogenesis of COVID-19.Int. J. Biol. Sci. 2022; 18: 5827-5848https://doi.org/10.7150/ijbs.77561Crossref Scopus (4) Google Scholar This mobilizes antigen-presenting cells (APCs)—including dendritic cells and pulmonary macrophages—that recognize PAMPs and DAMPs and release pro-inflammatory cytokines and chemokines, including interferon (IFN)-γ, IL-6, IP-10, and IL-1β. IL-1β further drives the activation of pro-inflammatory pathways, resulting in the recruitment of neutrophils and cytotoxic T cells and the upregulation of cytokines—mainly IL-6. Hypoxia induced by SARS-CoV-2 triggers further IL-6 secretion.8Farahani M. Niknam Z. Mohammadi Amirabad L. Amiri-Dashatan N. Koushki M. Nemati M. Danesh Pouya F. Rezaei-Tavirani M. Rasmi Y. Tayebi L. Molecular pathways involved in COVID-19 and potential pathway-based therapeutic targets.Biomed. Pharmacother. 2022; 145: 112420https://doi.org/10.1016/j.biopha.2021.112420Crossref Scopus (47) Google Scholar IL-6 also modulates its own expression by upregulating the production of IL-10 (anti-inflammatory). However, in the presence of SARS-CoV-2, there is significantly greater IL-6 production, resulting in a net pro-inflammatory state. Dysregulation of the innate immune response leads to increased inflammation and end-organ damage.9Gubernatorova E.O. Gorshkova E.A. Polinova A.I. Drutskaya M.S. IL-6: relevance for immunopathology of SARS-CoV-2.Cytokine Growth Factor. Rev. 2020; 53: 13-24https://doi.org/10.1016/j.cytogfr.2020.05.009Crossref PubMed Scopus (184) Google Scholar,10Islam H. Chamberlain T.C. Mui A.L. Little J.P. Elevated interleukin-10 levels in COVID-19: potentiation of pro-inflammatory responses or impaired anti-inflammatory action?.Front. Immunol. 2021; 12: 677008https://doi.org/10.3389/fimmu.2021.677008Crossref Scopus (62) Google Scholar One promising treatment modality for severe SARS-CoV-2 infection is EVs. EVs can secrete proteins and anti-inflammatory molecules that can modulate the host immune response. Additionally, EVs may act as a negative regulatory element in the transmission of viral infection.11Dogrammatzis C. Waisner H. Kalamvoki M. Cloaked viruses and viral factors in cutting edge exosome-based therapies.Front. Cell Dev. Biol. 2020; 8: 376https://doi.org/10.3389/fcell.2020.00376Crossref Scopus (21) Google Scholar Given these properties, EVs act at multiple points within the direct and indirect pathways to inhibit the inflammatory cascade (Figure 1). EVs can inhibit viral replication and thereby decrease direct viral injury.12Caobi A. Nair M. Raymond A.D. Extracellular vesicles in the pathogenesis of viral infections in humans.Viruses. 2020; 12: 1200https://doi.org/10.3390/v12101200Crossref Scopus (40) Google Scholar Their ability to block IL-6, IL-6 precursors (IL-1β), and inflammatory cytokines (tumor necrosis factor α [TNF-α], IL-8, and MIP-2) at multiple points within the pathway13Moon H.-G. Cao Y. Yang J. Lee J.H. Choi H.S. Jin Y. Lung epithelial cell-derived extracellular vesicles activate macrophage-mediated inflammatory responses via ROCK1 pathway.Cell Death Dis. 2015; 6: e2016https://doi.org/10.1038/cddis.2015.282Crossref PubMed Scopus (115) Google Scholar,14Weber B. Henrich D. Hildebrand F. Marzi I. Leppik L. The roles of extracellular vesicles in sepsis and systemic inflammatory response syndrome.Shock. 2023; 59: 161-172https://doi.org/10.1097/SHK.0000000000002010Crossref Scopus (1) Google Scholar while upregulating IL-10 results in downregulation of cytokine production and reduction in systemic injury. Given their ability to act on multiple pathways, EVs can provide a more comprehensive and effective approach to treating complex diseases.15Lener T. Gimona M. Aigner L. Börger V. Buzas E. Camussi G. Chaput N. Chatterjee D. Court F.A. Del Portillo H.A. et al.Applying extracellular vesicles based therapeutics in clinical trials – an ISEV position paper.J. Extracell. Vesicles. 2015; 4: 30087https://doi.org/10.3402/jev.v4.30087Crossref PubMed Scopus (844) Google Scholar To highlight the therapeutic properties of EVs, we conducted a review of 9 studies reporting the effects of EV therapy on lung injury models (Table 1). The reported outcomes of the reviewed EV therapies in experimental models (Table 1) indicate lung injury recovery, improved respiratory function, and overall survival. This was achieved by (1) reducing pro-inflammatory cytokines, (2) enhancing anti-inflammatory cytokines, (3) decreasing neutrophil infiltration, and (4) increasing macrophage polarization to the anti-inflammatory M2 phenotype. EV administration also resulted in downregulation of IL-1β, TNF-α, IL-6,16Wang X. Liu D. Zhang X. Yang L. Xia Z. Zhang Q. Exosomes from adipose-derived mesenchymal stem cells alleviate sepsis-induced lung injury in mice by inhibiting the secretion of IL-27 in macrophages.Cell Death Discov. 2022; 8: 18https://doi.org/10.1038/s41420-021-00785-6Crossref PubMed Scopus (11) Google Scholar,17Wang J. Huang R. Xu Q. Zheng G. Qiu G. Ge M. Shu Q. Xu J. Mesenchymal stem cell–derived extracellular vesicles alleviate acute lung injury via transfer of miR-27a-3p.Crit. Care Med. 2020; 48: e599-e610https://doi.org/10.1097/CCM.0000000000004315Crossref PubMed Scopus (72) Google Scholar,18Zhou Y. Li P. Goodwin A.J. Cook J.A. Halushka P.V. Chang E. Zingarelli B. Fan H. Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury.Crit. Care. 2019; 23: 44https://doi.org/10.1186/s13054-019-2339-3Crossref PubMed Scopus (134) Google Scholar MIP-1,18Zhou Y. Li P. Goodwin A.J. Cook J.A. Halushka P.V. Chang E. Zingarelli B. Fan H. Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury.Crit. Care. 2019; 23: 44https://doi.org/10.1186/s13054-019-2339-3Crossref PubMed Scopus (134) Google Scholar,19Bellio M.A. Young K.C. Milberg J. Santos I. Abdullah Z. Stewart D. Arango A. Chen P. Huang J. Williams K. et al.Amniotic fluid-derived extracellular vesicles: characterization and therapeutic efficacy in an experimental model of bronchopulmonary dysplasia.Cytotherapy. 2021; 23: 1097-1107https://doi.org/10.1016/j.jcyt.2021.07.011Abstract Full Text Full Text PDF Scopus (12) Google Scholar MIP-2, and CXCL2,18Zhou Y. Li P. Goodwin A.J. Cook J.A. Halushka P.V. Chang E. Zingarelli B. Fan H. Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury.Crit. Care. 2019; 23: 44https://doi.org/10.1186/s13054-019-2339-3Crossref PubMed Scopus (134) Google Scholar,20Hao Q. Gudapati V. Monsel A. Park J.H. Hu S. Kato H. Lee J.H. Zhou L. He H. Lee J.W. Mesenchymal stem cell–derived extracellular vesicles decrease lung injury in mice.J. Immunol. 2019; 203: 1961-1972https://doi.org/10.4049/jimmunol.1801534Crossref PubMed Scopus (68) Google Scholar in addition to upregulation of IL-10.16Wang X. Liu D. Zhang X. Yang L. Xia Z. Zhang Q. Exosomes from adipose-derived mesenchymal stem cells alleviate sepsis-induced lung injury in mice by inhibiting the secretion of IL-27 in macrophages.Cell Death Discov. 2022; 8: 18https://doi.org/10.1038/s41420-021-00785-6Crossref PubMed Scopus (11) Google Scholar,21Huang R. Qin C. Wang J. Hu Y. Zheng G. Qiu G. Ge M. Tao H. Shu Q. Xu J. Differential effects of extracellular vesicles from aging and young mesenchymal stem cells in acute lung injury.Aging. 2019; 11: 7996-8014https://doi.org/10.18632/aging.102314Crossref PubMed Scopus (74) Google Scholar,22Khatri M. Richardson L.A. Meulia T. Mesenchymal stem cell-derived extracellular vesicles attenuate influenza virus-induced acute lung injury in a pig model.Stem Cell Res. Ther. 2018; 9: 17https://doi.org/10.1186/s13287-018-0774-8Crossref PubMed Scopus (209) Google Scholar Moreover, EVs reportedly preserved alveolar structure,19Bellio M.A. Young K.C. Milberg J. Santos I. Abdullah Z. Stewart D. Arango A. Chen P. Huang J. Williams K. et al.Amniotic fluid-derived extracellular vesicles: characterization and therapeutic efficacy in an experimental model of bronchopulmonary dysplasia.Cytotherapy. 2021; 23: 1097-1107https://doi.org/10.1016/j.jcyt.2021.07.011Abstract Full Text Full Text PDF Scopus (12) Google Scholar reduced alveolar wall thickness,18Zhou Y. Li P. Goodwin A.J. Cook J.A. Halushka P.V. Chang E. Zingarelli B. Fan H. Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury.Crit. Care. 2019; 23: 44https://doi.org/10.1186/s13054-019-2339-3Crossref PubMed Scopus (134) Google Scholar,21Huang R. Qin C. Wang J. Hu Y. Zheng G. Qiu G. Ge M. Tao H. Shu Q. Xu J. Differential effects of extracellular vesicles from aging and young mesenchymal stem cells in acute lung injury.Aging. 2019; 11: 7996-8014https://doi.org/10.18632/aging.102314Crossref PubMed Scopus (74) Google Scholar,23Sun A. Lai Z. Zhao M. Mu L. Hu X. Native nanodiscs from blood inhibit pulmonary fibrosis.Biomaterials. 2019; 192: 51-61https://doi.org/10.1016/j.biomaterials.2018.10.045Crossref Scopus (7) Google Scholar and inhibited virus-induced apoptosis in lung epithelial cells.22Khatri M. Richardson L.A. Meulia T. Mesenchymal stem cell-derived extracellular vesicles attenuate influenza virus-induced acute lung injury in a pig model.Stem Cell Res. Ther. 2018; 9: 17https://doi.org/10.1186/s13287-018-0774-8Crossref PubMed Scopus (209) Google Scholar Finally, the ability of mesenchymal stem cell (MSC)-EVs to transfer cargo, such as miR-27a-3p, increased M2 macrophage polarization, effectively reducing TNF-α17Wang J. Huang R. Xu Q. Zheng G. Qiu G. Ge M. Shu Q. Xu J. Mesenchymal stem cell–derived extracellular vesicles alleviate acute lung injury via transfer of miR-27a-3p.Crit. Care Med. 2020; 48: e599-e610https://doi.org/10.1097/CCM.0000000000004315Crossref PubMed Scopus (72) Google Scholar and inhibiting lung fibrosis.24Cui H. Banerjee S. Xie N. Ge J. Liu R.-M. Matalon S. Thannickal V.J. Liu G. MicroRNA-27a-3p is a negative regulator of lung fibrosis by targeting myofibroblast differentiation.Am. J. Respir. Cell Mol. Biol. 2016; 54: 843-852https://doi.org/10.1165/rcmb.2015-0205OCCrossref PubMed Scopus (61) Google ScholarTable 1Articles reporting the effects of EV therapy on lung injury modelsSource of EVsModelSampleEV effects on cytokines and inflammatory moleculesPathological outcomesSourceAdipose MSCssepsis-induced ALI: in vivo mouselung tissueblood↓IL-6, ↓TNF-⍺, ↓IL-1β, ↑EBI3-protein, ↑P28-protein↓IL-27reduction in pulmonary inflammation and lung tissue injury (↓macrophage infiltration), increased survival rateWang et al.16Wang X. Liu D. Zhang X. Yang L. Xia Z. Zhang Q. Exosomes from adipose-derived mesenchymal stem cells alleviate sepsis-induced lung injury in mice by inhibiting the secretion of IL-27 in macrophages.Cell Death Discov. 2022; 8: 18https://doi.org/10.1038/s41420-021-00785-6Crossref PubMed Scopus (11) Google ScholarAmniotic fluidBPD: in vivo ratlung tissue↓IL-1⍺, ↓IL-1β, ↓MCP-1, ↓MIP-1⍺significant decrease of pulmonary hypertension, preservation of alveolar structure, reduction in vascular remodeling, suppression of lung inflammation, reduction of macrophage infiltrationBellio et al.19Bellio M.A. Young K.C. Milberg J. Santos I. Abdullah Z. Stewart D. Arango A. Chen P. Huang J. Williams K. et al.Amniotic fluid-derived extracellular vesicles: characterization and therapeutic efficacy in an experimental model of bronchopulmonary dysplasia.Cytotherapy. 2021; 23: 1097-1107https://doi.org/10.1016/j.jcyt.2021.07.011Abstract Full Text Full Text PDF Scopus (12) Google ScholarAdipose MSCsALI: in vivo mouseALI: in vitro mouselung tissueBALBMDMs↓TNF-⍺, ↓IL-1β, ↓IL-6, ↑IL-10, ↓iNOS, ↓NF-κB↓TNF-⍺, ↓IL-1β, ↓iNOS, ↑ YM-1, ↑MRC-1, ↑mi-27-a-3preduction of pulmonary endothelial barrier, inflammation (↓ pro-inflammatory cytokines, ↑ anti-inflammatory cytokines, ↓ neutrophils), and alveolar septal thickeningWang et al.17Wang J. Huang R. Xu Q. Zheng G. Qiu G. Ge M. Shu Q. Xu J. Mesenchymal stem cell–derived extracellular vesicles alleviate acute lung injury via transfer of miR-27a-3p.Crit. Care Med. 2020; 48: e599-e610https://doi.org/10.1097/CCM.0000000000004315Crossref PubMed Scopus (72) Google ScholarAdipose MSCsALI: in vivo mouseALI: in vitro mouselung tissueBALBMDMs↓IL-1β, ↑IL-10↓IL-6, ↑↓IL-1β, ↓TNF-⍺, ↓iNOS, ↑TGF-β1, ↑YM-1reduction in inflammation (↓ neutrophils, ↓macrophage recruitment) and alveolar wall thicknessHuang et al.21Huang R. Qin C. Wang J. Hu Y. Zheng G. Qiu G. Ge M. Tao H. Shu Q. Xu J. Differential effects of extracellular vesicles from aging and young mesenchymal stem cells in acute lung injury.Aging. 2019; 11: 7996-8014https://doi.org/10.18632/aging.102314Crossref PubMed Scopus (74) Google ScholarBone marrow MSCsALI: in vivo mouseALI: in vitro mouseBALRAW267.4↓MIP-2, ↓TNF-⍺, ↑LTB4↓MRP1-protein, ↑miR-145antimicrobial effect (↑ monocyte phagocytosis, ↓bacterial levels), reduction of inflammation (↓leukocytes, ↓neutrophils)Hao et al.20Hao Q. Gudapati V. Monsel A. Park J.H. Hu S. Kato H. Lee J.H. Zhou L. He H. Lee J.W. Mesenchymal stem cell–derived extracellular vesicles decrease lung injury in mice.J. Immunol. 2019; 203: 1961-1972https://doi.org/10.4049/jimmunol.1801534Crossref PubMed Scopus (68) Google ScholarUmbilical cord jelly MSCsinfluenza-induced ALI: in vitro humanAECno particular mechanism studiedrestoration of alveolar fluid clearance, reduction alveolar protein permeability29Umbilical cord EPC (rich in miR-126)ALI: in vivo mouseALI: in vitro humanlung tissueBALAEC↓TNF-⍺, ↓IL-1β, ↓IL-6, ↓IFN-γ, ↓MIP-1↓MIP-2, ↓MIG, ↓IP-10, ↓MPO↑Claudin1, ↑Claudin4, ↑Occludinreduction of inflammation (↓ pro-inflammatory cytokines, ↑ anti-inflammatory cytokines, ↓ neutrophils), alveolar wall thickness, and hyaline membrane formationZhou et al.18Zhou Y. Li P. Goodwin A.J. Cook J.A. Halushka P.V. Chang E. Zingarelli B. Fan H. Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury.Crit. Care. 2019; 23: 44https://doi.org/10.1186/s13054-019-2339-3Crossref PubMed Scopus (134) Google ScholarWhole bloodfibrosis: in vivo mouselung tissue↓hydroxyprolinereduction of immune cell recruitment, alveolar wall thickness, and collagen depositionSun et al.23Sun A. Lai Z. Zhao M. Mu L. Hu X. Native nanodiscs from blood inhibit pulmonary fibrosis.Biomaterials. 2019; 192: 51-61https://doi.org/10.1016/j.biomaterials.2018.10.045Crossref Scopus (7) Google ScholarBone marrow MSCsinfluenza-induced ALI: in vivo piginfluenza-induced ALI: in vitro pigslung tissueLECs↓TNF-⍺, ↓CXCL10, ↑IL-10↓apoptosisinhibition of viral replication, reduction of inflammation, decrease in virus-induced lung lesions, inhibited virus-induced apoptosis in lung epithelial cellsKhatri et al.22Khatri M. Richardson L.A. Meulia T. Mesenchymal stem cell-derived extracellular vesicles attenuate influenza virus-induced acute lung injury in a pig model.Stem Cell Res. Ther. 2018; 9: 17https://doi.org/10.1186/s13287-018-0774-8Crossref PubMed Scopus (209) Google ScholarAECs, alveolar epithelial cells; ALI, acute lung injury; BAL, bronchioalveolar lavage; BMDMs, bone marrow-derived macrophages; BPD, bronchopulmonary dysplasia; CXCL, chemokine (C-X-C motif) ligand; EPC, endothelial progenitor cell; EVs, extracellular vesicles; IFN, interferon; IL, interleukin; LECs, lymphatic endothelial cells; LTB4, leukotriene B4; MCP, monocyte chemotactic protein; MIG, monokine induced by gamma interferon; MIP, macrophage induced protein; MIR, microRNA; MPO, myeloperoxidase; MRC-1, mannose receptor C-type 1; MRP1, multidrug resistance associated protein 1; MSC, mesenchymal stem/stromal cell; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; NOS, nitric oxide synthase (iNOS, inducible; eNOS, endothelial); RAW267.4, monocyte/macrophage lineage; TGF, transforming growth factor; TNF, tumor necrosis factor; YM-1, Chitinase 3-like 3, a macrophage protein. Open table in a new tab AECs, alveolar epithelial cells; ALI, acute lung injury; BAL, bronchioalveolar lavage; BMDMs, bone marrow-derived macrophages; BPD, bronchopulmonary dysplasia; CXCL, chemokine (C-X-C motif) ligand; EPC, endothelial progenitor cell; EVs, extracellular vesicles; IFN, interferon; IL, interleukin; LECs, lymphatic endothelial cells; LTB4, leukotriene B4; MCP, monocyte chemotactic protein; MIG, monokine induced by gamma interferon; MIP, macrophage induced protein; MIR, microRNA; MPO, myeloperoxidase; MRC-1, mannose receptor C-type 1; MRP1, multidrug resistance associated protein 1; MSC, mesenchymal stem/stromal cell; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; NOS, nitric oxide synthase (iNOS, inducible; eNOS, endothelial); RAW267.4, monocyte/macrophage lineage; TGF, transforming growth factor; TNF, tumor necrosis factor; YM-1, Chitinase 3-like 3, a macrophage protein. The translation of EV-based therapies from acute lung injury models to human clinical studies have significant potential for the treatment of SARS-CoV-2-induced acute respiratory distress syndrome (ARDs). Preclinical models of lung injury have shown upregulated inflammatory responses and migration of neutrophils and macrophages to pulmonary tissues (Table 1). This was verified pathologically and shown to be due to an upregulation of IL-6. In preclinical models, EVs have demonstrated an ability to dampen inflammation and reduce T cell proliferation caused by SARS-CoV-2, establishing the rationale for present clinical trials.25del Rivero T. Milberg J. Bennett C. Mitrani M.I. Bellio M.A. Human amniotic fluid derived extracellular vesicles attenuate T cell immune response.Front. Immunol. 2022; 13: 977809https://doi.org/10.3389/fimmu.2022.977809Crossref Scopus (2) Google Scholar Several EV-based therapies have entered clinical trials with the aim of assessing safety, efficacy, administration route, and optimal dosing in various respiratory conditions. A complete list of ongoing clinical trials on the use of EV-based therapeutics in COVID-19 treatment is shown in Table 2. Due to the rapid spread of COVID-19 and lack of effective therapies, several studies were approved on an emergency basis by ethical committees. In a study where amniotic fluid-derived EVs were administered to high-risk patients with mild-to-moderate COVID-19, results showed a significant decrease in CRP, IL-6, and TNF-α, as well as stabilized absolute lymphocyte count (ALC).26Bellio M.A. Bennett C. Arango A. Khan A. Xu X. Barrera C. Friedewald V. Mitrani M.I. Proof-of-concept trial of an amniotic fluid-derived extracellular vesicle biologic for treating high risk patients with mild-to-moderate acute COVID-19 infection.Biomater. Biosyst. 2021; 4: 100031https://doi.org/10.1016/j.bbiosy.2021.100031Crossref Scopus (7) Google Scholar Additional clinical testing performed on three severely ill patients with COVID-19 revealed a decrease in inflammatory biomarkers and improvements in patient clinical status and respiratory function.27Mitrani M.I. Bellio M.A. Sagel A. Saylor M. Kapp W. VanOsdol K. Haskell G. Stewart D. Abdullah Z. Santos I. et al.Case report: administration of amniotic fluid-derived nanoparticles in three severely ill COVID-19 patients.Front. Med. 2021; 8: 583842https://doi.org/10.3389/fmed.2021.583842Crossref PubMed Scopus (25) Google Scholar Both studies were completed without any adverse events or safety concerns.Table 2List of clinical trials on the use of EV-based therapeutics in COVID-19 managementReferenceaObtained from clinicaltrials.gov using "extracellular vesicles" or "exosomes" as search strings, with results restricted to COVID-19.Official titleStatusNCT04493242Extracellular Vesicle Infusion Treatment for COVID-19 Associated ARDS (EXIT-COVID19)completedNCT05787288A Clinical Study on Safety and Effectiveness of Mesenchymal Stem Cell Exosomes for the Treatment of COVID-19recruitingNCT04657458Expanded Access for Use of bmMSC-Derived Extracellular Vesicles in Patients With COVID-19 Associated ARDSavailableNCT05116761ExoFlo™ Infusion for Post-Acute COVID-19 and Chronic Post-COVID-19 Syndromenot yet recruitingNCT05354141Bone Marrow Mesenchymal Stem Cell Derived EVs for COVID-19 Moderate-to-Severe Acute Respiratory Distress Syndrome (ARDS): A Phase III Clinical TrialrecruitingNCT05228899Zofin to Treat COVID-19 Long HaulersrecruitingNCT04902183Safety and Efficacy of Exosomes Overexpressing CD24 in Two Doses for Patients With Moderate or Severe COVID-19recruitingNCT05216562Efficacy and Safety of EXOSOME-MSC Therapy to Reduce Hyper-inflammation In Moderate COVID-19 Patients (EXOMSC-COV19)recruitingNCT04798716The Use of Exosomes for the Treatment of Acute Respiratory Distress Syndrome or Novel Coronavirus Pneumonia Caused by COVID-19 (ARDOXSO)not yet recruitingNCT05387278Safety and Effectiveness of Placental Derived Exosomes and Umbilical Cord Mesenchymal Stem Cells in Moderate to Severe Acute Respiratory Distress Syndrome (ARDS) Associated With the Novel Corona Virus Infection (COVID-19)recruitingNCT04491240Evaluation of Safety and Efficiency of Method of Exosome Inhalation in SARS-CoV-2 Associated Pneumonia. (COVID-19EXO)completedNCT04384445Zofin (Organicell Flow) for Patients With COVID-19active, not recruitingNCT04657406Expanded Access to Zofin for Patients With COVID-19availablea Obtained from clinicaltrials.gov using "extracellular vesicles" or "exosomes" as search strings, with results restricted to COVID-19. Open table in a new tab The ongoing COVID-19 pandemic caused by SARS-CoV-2 highlights the critical need for effective therapies to mitigate disease progression and reduce severity. EV-based therapeutics have shown the capacity to attenuate the hyper-inflammatory response caused by SARS-CoV-2 and promote repair of damaged lung tissue in preclinical models, with similar results when translated into SARS-CoV-2 patients. In addition, EVs may harbor therapeutic applications to tackle the prolonged symptoms of infection (long COVID) that are associated with prolonged overactivation and exhaustion of immune cells.28Phetsouphanh C. Darley D.R. Wilson D.B. Howe A. Munier C.M.L. Patel S.K. Juno J.A. Burrell L.M. Kent S.J. Dore G.J. et al.Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection.Nat. Immunol. 2022; 23: 210-216https://doi.org/10.1038/s41590-021-01113-xCrossref PubMed Scopus (202) Google Scholar The overview presented in this work highlights the innovative use of EVs as a promising approach to address severe SARS-CoV-2 infections. Recent progress in clinical trials has also laid the groundwork for the development of effective EV-based therapies for a broad range of viral infections. Y.L. would like to acknowledge the mentors who have played a profound role in their career development and to the patients who inspire them to strive for greatness daily. Y.L. also wants to acknowledge MSSN for its support of scholarly endeavors. Funding: Funding information is not applicable. Y.L., idea conception; primary author for design, framework, and refinement of severe SARS-CoV-2 model, EVs as a therapeutic agent against severe SARS-CoV-2; review of literature; summarizing and organizing of data; main manuscript writing contribution; participation in post-peer review manuscript revisions. G.G., primary author for introduction, extracellular vesicle therapy, and future direction and conclusion. M.J., main manuscript writing; literature review; addition of substantial, clinically oriented written content. G.P.M., main manuscript writing; literature review; addition of substantial, clinically oriented written content. A.V.d.K., main manuscript writing; literature review; addition of substantial, clinically oriented written content. M.I.M., editing and revision of manuscript. M.A.B., editing and revision of manuscript. T.d.R., editing and revision of manuscript. All authors read, reviewed, and approved the final manuscript. G.G., M.I.M., T.d.R., and M.A.B. are employees of Organicell Regenerative Medicine. M.I.M. is the Chief Science Officer, serves on the Organicell Regenerative Medicine Board of Directors, and holds equity in the company.